Acropora with poor polyp extension

[mrg02d]

Hello,
I got this mystery acropora about 1.5 months ago. Not sure what kind it is, but its purple with green polyps. Has a very large base and several spikey growths. Looks alot like the purple bonsai acroporas I have seen online.

Anyways, it seems to NEVER have its polyps out much. The only way I see them is with actinic light causing them to glow. My other acroporas all show their polyps. Any ideas whats wrong with it? Should I try putting it down on the bottom of the tank? Its up at the top right now under T5 lights.

Thanks!
Matt

 

[dannyb]

Actinic lights help and promote the growth of coral, It might not be getting the light needed.

 

[melosu58]

How about your water test results?

 

[neilanh]

How much flow is it getting where you have it? Try moving it - if it's currently in a high flow area, move it to somewhere with less flow, or vice-versa.

 

[cmor1701d]

I agree with the above.
Please post all the water parameters.
What is is lighting system (make/model) and how old are the T5 bulbs.

Is anything else near this sps? Any lps or other corals that might be stinging it?

 

[mrg02d]

Hello,
Tank size: 20g
Water Parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 0 (questionable) Brown whispy algea present
Phosphate: 0 (questionable)
dKH: 9-10
Calcium: 500ppm
pH: 8.2
Salinity: 1.025
Temp: 78F
Placement is at the top, right under two koralia powerheads (a koralia 1 and a koralia 2) pointed to the surface opposing each other. A few other SPS nearby at the top with it. No potential stingers, but there are mushrooms, zoas, and various LPS in the tank.
Lighting is from a 24in 96W (4 bulb) T5 Current USA Sundial with 2-wavepoint blue bulbs, 1-URI aquasun, and 1-wavepoint 12000k bulb. These are all about 5-6months old. They are all being replaced by ATI bulbs (2-aquablue and 2-blue plus).

I moved the coral down to the lower portion of the tank.
I am running Clearmax (GFO) in my Fluval 305 as well as some carbon. There is also a small mass of chaeto in the tank that has the output of the fluval 305 blasting it and a CFL bulb above the chaeto to light it.

Polyp extension has been very minimal since I brought it home, yet the others seem to have their polyps out 24 hours a day.

Not sure what kind this is. I am betting its not bonsai after looking that up and seeing the prices! I paid $20 for this one from my LFS. Much larger than the $90 frags I see online, so I am guessing its some other purple acropora with green polyps.

Thanks!
Matt